Campylobacter jejuni is a leading cause of human gastroenteritis worldwide. This study aimed at a better understanding of the genetic diversity of this pathogen disseminated in Japan. We performed multilocus sequence typing (MLST) of Campylobacter jejuni isolated from different sources (100 human, 61 poultry, and 51 cattle isolates) in Japan between 2005 and 2006. This approach identified 62 sequence types (STs) and 19 clonal complexes (CCs), including 11 novel STs. These 62 STs were phylogenetically divided into 6 clusters, partially exhibiting host association. We identified a novel ST (ST-4526) that has never been reported in other countries; a phylogenetic analysis showed that ST-4526 and related STs showed distant lineage from the founder ST, ST-21 within CC-21. Comparative genome analysis was performed to investigate which properties could be responsible for the successful dissemination of ST-4526 in Japan. Results revealed that three representative ST-4526 isolates contained a putative island comprising the region from Cj0737 to Cj0744, which differed between the ST-4526 isolates and the reference strain NCTC11168 (ST-43/CC-21). Amino acid sequence alignment analyses showed that two of three ST-4526 isolates expressed 693aa- filamentous hemagglutination domain protein (FHA), while most of other C. jejuni strains whose genome were sequenced exhibited its truncation. Correspondingly, host cell binding of FHA-positive C. jejuni was greater than that of FHA-truncated strains, and exogenous administration of rFHA protein reduced cell adhesion of FHA-positive bacteria. Biochemical assays showed that this putative protein exhibited a dose-dependent binding affinity to heparan sulfate, indicating its adhesin activity. Moreover, ST-4526 showed increased antibiotic-resistance (nalidixic acid and fluoroquinolones) and a reduced ability for DNA uptake. Taken together, our data suggested that these combined features contributed to the clonal thriving of ST-4526 in Japan.

Aims: Campylobacter jejuni is a major cause of foodborne gastroenteritis. We previously reported the widespread Camp. jejuni sequence type ( Significance and Impact of the study: This is the first evidence of the continued thriving of ST-4526/ST-4253 in Japan with their increased in vivo fitness. Our findings suggest that poultry mediates the microevolution of this pathogen, thereby enabling these STs to become widespread.

Although there have been several reports on the efficacy assessment of a Salmonella enterica serovar Enteritidis vaccine against intestinal and parenchymatous organ diseases of laying hens, no public health risk characterization of its long-term effect on eggs has been reported. In this study, we attempted to assess the public health effect of an inactivated S. enterica serovar Enteritidis vaccine against serovar Enteritidis contamination of chicken eggs. We analyzed serovar Enteritidis isolation test results from four windowless farms in which inactivated-vaccine administration was initiated based on the sanitary monitoring program of a farm. When flocks with and without S. enterica serovar Enteritidis vaccine treatments were mixed, the application of an inactivated serovar Enteritidis vaccine decreased the most probable number (MPN) of bacteria by at least 100-fold in broken (liquid) egg samples positive for serovar Enteritidis, although a statistical difference between those MPNs could not be obtained. The isolation frequency after the vaccine application was less than 1/10 (P < 0.01). No S. enterica serovar Enteritidis bacteria were isolated approximately 1 year after all of the chickens had received the inactivated serovar Enteritidis vaccine. It was suggested that an adequate administration of an inactivated serovar Enteritidis vaccine reduced the contamination risk of eggs (the number of isolated serovar Enteritidis cells and detection frequency) compared to the contamination risk of eggs laid by nonvaccinated hens.The microorganism risk of food and food materials has been studied in order to be characterized

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Environmental isolates of Salmonella enterica serover Enteritidis (S. Enteritidis) clones were grown to the logarithmic phase, washed and re-suspended in saline or Luria-Bertani (LB) medium, and then 10-µL aliquots of the suspensions were dried overnight at room temperature. The dried bacteria were mixed with 1 mL of ice-cold PBS, suspended and examined for colony-forming activity. All of the pathogenic clones with high levels of SEp22, identical to Salmonella Dps, maintained good viability if suspended in LB medium prior to drying. However, none of the nonvirulent strains, exhibiting low levels of SEp22, survived. Similar results were obtained with sep22-knocked out mutants, suggesting that SEp22 is important for the acquisition of dry-resistance. Nutritional factors, such as LB medium, cabbage extracts, and egg yolk but not egg white, were shown to be necessary for the acquisition of dry-resistance, because none of the clones remained viable irrespective of SEp22 expression if suspended in saline. Scanning electron micrograms also supported the importance of nutrition, showing re-growth of the bacteria after drying in LB but not in saline. These results suggest the importance of both SEp22 expression and nutrients for the acquisition of dryresistance by S. Enteritidis.